Think this has now been answered. However, the answer goes for almost all television productions. There are floor monitors that show program output, and another showing "preview". Which is the next shot. The director will direct the camera guys to get a certain shot, then say "coming to 1, on 1". To add to the previous answer on this. "In vision" isn't a term for "camera two is on". In vision is the name of a certain shot. Also known as the "wide shot". This is the shot of both presenter and guest and the whole set.
The cameras are set up, left to right, from viewers perspective, camera 1,2,3.
1 - wide shot / in vision
2 - medium close up shots
3 - proper close up shots
There's also a "jib" camera. That's a camera on a long pole essentially to give higher shots and more dynamic shots with interesting movements.
Presenters know the camera they are on in a few ways:
Red indication light on camera that's live
Director vocal cues
Program monitor on studio floor
Floor manager standing behind the live camera
Floor manager pointing to the live camera
